1. Field of the Invention
The present invention relates to a magnetic recording medium. More particularly, it relates to a magnetic recording medium which has an electromagnetic transfer characteristic and satisfactory physical characteristics such as a repeated running durability and an adhesive strength and also has a surface smoothness.
2. Description of the Prior Art:
It has been mainly used as a magnetic recording medium a product prepared by coating a magnetic paint comprising a magnetic powder and a resin binder, on a substrate such as film made of polyacetate, polyvinyl chloride or polyester. Various binders have been proposed as the binders used in the magnetic paint. However, a magnetic recording medium having both of satisfactory electromagnetic transfer characteristics and satisfactory physical characteristics of the repeated running durability and the adhesive strength, has not been found.
The combination of the two components of said magnetic powder and a binder such as urethane resins, vinyl acetate resins, nitrocellulose resins and epoxy resins has been mainly used. It has been, however, difficult to satisfy both characteristics by said combination of said two components.
The inventors have studied various characteristics of the resin binders which have been previously used and have found that both characteristics can be achievied by combining three components of the urethane resin, the epoxy resin and the nitrocellulose at specific ratios. The present invention has been attained by said finding.